Venkatesh,
Your question is little subjective as some times based on database vendor type a schema can be called as a separate database.. For all purposes they are separate schema
The Central Management Server (CMS) collects audit information from the other BI platform servers and writes the details to the Auditing Data Store (ADS), known as the Auditing database. This information lets System Administrators manage their BI platform environment, and content usage, through reporting and analysis of ADS data...
Also check a nice blog by one of my old colleague below... this explains Auditing in very detail